Assiqnob to wabben



Dec. 22,1925. 1,566,749

IMHOFF APPARATUS FOR USE IN H OT GALVANIZING AND THE LIKE Filed April 16, 1925 INVENTUR Wallace Imhol-Z- be his affa rn eq Patented Dec. '22, 1925'.

'* UNITED STATESPATENTO FFICEiL w on}. QIYPHTSBURGH, mmzsnvamg assrenon r waaaan a. smrrn, 01 mawxoax-hu. Y. i q g 'nrm'rus o: use In nor. envmmm mun Lima To 'all 'w-Iz'om may concern: i

. Be it known that I, WALLACE G. 1mm,

a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in an Apparatus for Use in Hot Galvanizing and the like, of

cles being galvanized are assed through abath of molten zinc maintained at a tem' erature of approximatel 820 degrees Fa renheit to 950 degrees ahrenheit. Such bath usually containsa small percentage of cer.

tain other metals, such as tin, antimony,land

' aluminum. This bath is contained in a ves- .'sel,'known1n the trade as a galvanizing kettle, the sides of which are commonly made of fire-box steel and the bottom and ends of flange steel, or boiler steel. part of the permanent equipment is a thermometer, or pyrometer, for taking-the temperature of v the bath. This is enclosed in a casing which extends below the surfaceof the molten zinc.

The great difficulty encountered. in the process of hot galvanizing is-that the molten. zinc gradually dissolves an? metal with which it is in contact for any ength of time, forming a zinc alloy known as vdross.

It is further 'a fact that molten zinc is possessed of highly penetrative properties,

so that it permeates the ores, or microscopic apertures, in a'metallic ody.' 'As the dr oss itself when formed furnishes no protection to the still unattacked body of metal, the

action of the molten zinc is progressive, terminating only with the complete destruction,

or dissolution, of the body with which it comes in contact.

The dissolving action of the zinc involves a great loss in the destruction of izing kettles, sive, and in the destruction of the pyrometer tubes which contain thethermometer or thermo-cou'ple for regulating the temperature of the bath. For this reason extensive experiments have been carried out for the the galvanpurpose of discovering a metal, or metallic alloy, which would not molten zinc.

be attacked by \Vith this object in view experiments were made with nickel, Monel Application am A' i-n 1a, 1923. semi m5. sealer.

galvanizing apparatus and other arwhich are necessarily. expen meta]; duriron, c alite, resistaL I wrought iron, castiron, all kindsofsteel; and with substantially all ferrous and-other alloys in common or scientific use. metals and all alloys tested, however, were found to be attacked-in varyinggdegrees; the molten zmc. I The fact that certam alloys were capable of tacks by variousacids has proven *to: be no criterion of their ability to resist the attacks of molten zinc. I 1

Yariousroatings applied to the metal as by a annlng, calorizmg, or-parkerizingx-the tecting themetal from the molten zinc.*

The ob ect of the present invention is, therefore, to. provide metallic. articles, ticularly galvanizing kettles and thermome-v ter and pyrometerjcasingswith a coating ca. pable of effectually protecting the same from the dissolving actlon of molten zinc.

I' have succeeded in effecting this purpose" tective coat1ng' havlng a SlllQlOllSbflSBi, I

have dlscovered that certain silicates, and,

by applying to the metallic articles ,a

dense or highly glazed or vitreous surface. Such coating serves as an. impermea ble medium interposed between the metal of the article and the bath, and which is itself unaffected by the action of the molten zinc,

The accompanying drawings show in cross section 'a galvanizing kettle and thermometer tube of the present nvention."

In such drawings the reference numeral 1 designates the usual refractoryjsetting for such a provided with the protection resisting oxidation;- .orz ata par-Q the kettle, 2 the draft apertures through such I setting, and 3 the filling of coke which is burned to heat the kettle and the zinc which it contains.

The galvanizing kettle'is shown as con-' structed in the usual manner with sides4 of relativel thick plates of fire box steel, and with en s and cured to the sides by rivets or the like. A tubular casing 6, provided with a thermometer 7, is shown projecting downwardly into the body of the kettle. The interior surface bottom'5 of flange steel se-' of. both the sides, bottom, and ends of kettle is provided with a protective coating 8 of enamel.

'The preferred enamel for. this purpose is one of a hi hly refractory character, having 8. highly g principal co'm silica and bone oxide,

nents of such .enamel are comblned wlth alumina and other oxides ascalcium oxide, so-

dium oxide, potassium oxide. The relative proportions of these com nents may be varied within relatively wi e limits, but I prefer those mixtures which are .baked on at from 1000 degrees Fahrenheit to 1500 de- Fahrenheit, and which give a highly glazed surface." It maybe stated as a. general rul'e that thepercentages of silica and boric oxide in the enamel should'be so proportioned as to im enamel coat1ng;- "silica, bOIlQ-OXldQ, and alumina, together i may desir complete coating. The exterior surface "of the thermometer .or pyrometer casing is provided with a similar coat ng of enamel,

which is similarly baked on.

It has been proved that such coating is effective in protecting metals from theattacks of molten zinc; and such effectiveness may be attributed to the fact that the sili- Hcates formingits chief com nent are not themselves subject to the so vent action of molten zinc at galvanizing temperatures, and

to the fact that the glazed surface of the enamelis capable of resisting the penetrathe ename tiveaction of the. molten zinc.

It will be reciated from the compositioi'i of employed, that a coatmg of the same constitutes a good heat conducting medium. It does not, therefore, retard the melting of spelter in a galvanizing kettle, or impair the functioning of a'thermometer imr d y p mersed in the bath. 7 1

j It will be understood that the method of protecting articles from the attacks of molten zmc may be utilized for other purazed or vitreous" surface. The

poses than the protection of galvanizing kettles and the thermometer and pyrometer casings used therewith. For example a similar otective coating may be applied to mol s for casting zinc slabs at the melters, and to the interior surface of tubes for conveying molten zinc, or for other similar purposes.

What I claim is:

1. Apparatus for hot galvanizing and the like comprising a galvanizing kettle-having a body of ferrous metal, and a coating of an enamel comprising a complex aluminum b'oro-s111cate as the basis thereof on the .intenor surface of the bodyof the kettle, to provlde a heat conducting medium for protecting the same from the solvent action of molten zinc contained in the kettle.

' 2. In apparatus foruse in hot galvanizing and the like, an article to be' brought into contact with molten zinc comprising a. metal-. l1cbody, sald body having a coatingof an enamel comprising a complex aluminum .boro-sllicate as the basis thereof on the surface of the body which comes into'contact with the molten zinc to provide a heat conductmg medium for protecting the body of the article from the solvent action of the molten zinc.

3. In apparatus for use in hot galvanizing .and the like, an article to be brought into contact with molten zinc comprising a metal- 11c body, said body having a coating ofv an enamel comprising a complex aluminum 'bor'o-slllcate as the basis thereof together with boric-oxide on the surface of the whlch comes into contact with the molten zmc to provide a heat conducting medium for protecting the body of the article from the action of the molten zinc.

4. In apparatus for use in hot galvanizing and the like, an article to be brought into contact with molten zinc comprising a metallic body, said body having a coating of an enamel comprising a complex aluminum bore-silicate as the basis, thereof together with boric-oxide and at least one metallic oxide on the surface of the body which comes into contact with the molten zmc to provide,

a heat conducting medium for protectin-gthe body of the article from the action of the molten zinc.

In witness whereof,

I hereunto my hand.

- WALLACE G. IMHOFFL 

